Assessment of coronary plaque progression in coronary computed tomography angiography using a semiquantitative score.

OBJECTIVES: We sought to describe the progression of coronary atherosclerotic plaque over time by computed tomography (CT) angiography stratified by plaque composition and its association with cardiovascular risk profiles.
BACKGROUND: Data on the progression of atherosclerosis stratified by plaque composition with the use of noninvasive assessment by CT are limited and hampered by high measurement variability.
METHODS: This analysis included patients who presented with acute chest pain to the emergency department but initially showed no evidence of acute coronary syndromes. All patients underwent contrast-enhanced 64-slice CT at baseline and after 2 years with the use of a similar protocol. CT datasets were coregistered and assessed for the presence of calcified and noncalcified plaque at 1 mm cross sections of the proximal 40 mm of each major coronary artery. Plaque progression over time and its association with risk factors were determined. Measurement reproducibility and correlation to plaque volume was performed in a subset of patients.
RESULTS: We included 69 patients (mean age 55 +/- 12 years, 59% male patients) and compared 8,311 coregistered cross sections at baseline and follow-up. At baseline, any plaque, calcified plaque, and noncalcified were detected in 12.5%, 10.1%, and 2.4% of cross sections per patient, respectively. There was significant progression in the mean number of cross sections containing any plaque (16.5 +/- 25.3 vs. 18.6 +/- 25.5, p = 0.01) and noncalcified plaque (3.1 +/- 5.8 vs. 4.4 +/- 7.0, p = 0.04) but not calcified plaque (13.3 +/- 23.1 vs. 14.2 +/- 22.0, p = 0.2). In longitudinal regression analysis, the presence of baseline plaque, number of cardiovascular risk factors, and smoking were independently associated with plaque progression after adjustment for age, sex, and follow-up time interval. The semiquantitative score based on cross sections correlated closely with plaque volume progression (r = 0.75, p < 0.0001) and demonstrated an excellent intraobserver and interobserver agreement (kappa = 0.95 and kappa = 0.93, respectively).
CONCLUSIONS: Coronary plaque burden of patients with acute chest pain significantly increases during the course of 2 years. Progression over time is dependent on plaque composition and cardiovascular risk profile. Larger studies are needed to confirm these results and to determine the effect of medical treatment on progression.